禄丰古猿带状牙釉质发育不全的再观察

牙釉质发育不全是反映牙齿发育过程中遭遇生理性刺激的有效指标。本文对来自云南禄丰石灰坝的禄丰古猿(Lufengpithecus lufengensis)261枚单颗恒齿进行观察分析,发现223枚牙齿普遍罹患带状牙釉质发育不全(LEH),比例为85.4%,高于其它已报道过的中新世古猿、化石人科成员及现生大猿。另一方面,用扫描电镜和数码显微镜着重分析了12枚犬齿,均有多条LEH,且雄性犬齿的LEH条数多于雌性;相邻LEH间的釉面横纹数在14-25条之间。结合禄丰古猿釉面横纹的生长周期(9天),估算相邻LEH之间的时间间隔为4.8-6.6月,季节性营养不良可能是禄丰古猿釉质发育不全的主要原因。

New Observations of Linear Enamel Hypoplasia from Late Miocene Lufengpithecus lufengensis of Yunnan,South China

The expression of linear enamel hypoplasia (LEH) has been used as a dental indicator of generalized physiological stress during dental development in living and fossil primates. Here, we present the expression of LEH in Late Miocene large-bodied hominoid fossils Lufengpithecus lufengensis from Yunnan, China. Previous studies have shown that Lufengpithecus lufengensis mandibular teeth exhibited high frequencies of LEH and the periodicity of rLEH showed a semi-annual pattern. As an extension, this present study focuses on 261 isolated permanent teeth of Lufengpithecus lufengensis to assess their LEH prevalence and periodicity of rLEH. In the prevalence analysis, 261 isolated permanent teeth were examined with 85.4 % (223 of 261) affected by LEH. For periodicity of rLEH, 12 canines are analyzed by scanning electron microscopy (SEM Hitachi S-3700) and Keyence VHX-600EOS digital microscope. The results showed that LEH defects occurred repeatedly at a range of 4.8-6.6 months (an average of 6 months) in Lufengpithecus lufengensis. Male canines exhibit more LEH than female. Based on the analysis on the palaeoenvironment and diet of Lufengpithecus lufengpithecus, while seasonal cycles can influence both disease and nutritional stress, it is likely that seasonal variation in fruiting cycles results in higher LEH incidence in Lufengpithecus lufengensis.